Fabrication of printed circuit boards (PCB), such as motherboards may require high accuracy measurements of solder paste deposit volume, height, and alignment on all areas of the PCB, for example, after the paste print step in the surface mount technology (SMT) process. The required resolution may be measured in the sub-micron regime as package sizes are decreasing and the feature size and their pitch are following suit. However, the commercially available light field imaging may not be used for this purpose at this time, and moreover may not satisfy the high resolution requirement.
There is also a need to monitor how much a PCB and/or the components disposed on it may deform when the PCB is taken through the SMT reflow oven. Such measurements may need to be conducted in-situ, which means the imaging apparatus may need to travel along with the PCB through the oven. However, the space available above the board inside the oven is limited and may reach about 50 mm, so a provision of the imaging apparatus in-situ may face substantial technological constraints.